Over the last decade NIR spectroscopy has increasingly developed to an indispensable analytical tool for production and quality control in the pharmaceutical industry. Qualitative NIR investigations are frequently applied in the identity control of incoming raw materials, whereas quantitative analysis of the final product is an important step in the pharmaceutical process chain. However, the majority of pharmaceutical analyses is still performed by taking a sample from the production site and transporting it to a remote quality control laboratory. This delay between sampling and availability of results limits the frequency of analysis and the optimization of the production line. Thus, novel portable field instrumentation capable of performing a rapid at-line or in-line analysis of the process can be considered as a key tool to advance the effectiveness of the pharmaceutical industry.
Older versions of compact spectrometers, such as the ones disclosed in United States Patent Publication 2012/0188541, published Jul. 26, 2012 to Ocean Optics, Inc, and 2005/0007596, published Jan. 13, 2005 in the name of Wilks Enterprise, Inc. attempt to minimize their footprint by providing a series of optical path folding mirrors. Unfortunately, folding mirrors require extensive alignment procedures during manufacture, and do not provide a very robust structure for field-use devices resulting in low or unpredictable performance.
Historically, light conduits, light pipes or light transfer conduits were used for light beam shaping or light redirection applications. Examples are display engine technologies for displays or front projection television applications, such as those disclosed in U.S. Pat. Nos. 7,252,399 and 7,033,056; and United States Patent Application No. 2006/0044833. U.S. Pat. No. 6,420,708, issued Jul. 16, 2002 to Wilks et al, discloses a spectrum analyzer, which includes a rectangular light pipe or crystal for transmitting light to a sample, but not for shaping the reflected light for delivery to a filter.
U.S. Pat. Nos. 6,473,165; 7,006,204; and 7,184,133 relate to automated verification systems in which the reflectance of two separate beams of light at two different angles of incidence reflected off of an optical interference security feature are measured and compared. A converging tapered light pipe is disclosed for collecting and concentrating light.
An object of the present invention is to overcome the shortcomings of the prior art by providing a high-performance, robust, portable, low-power spectrometer including a broadband light source and detector array for use in an in-the-field sample testing device.